Air duct damper



June 2, 1942. J. E. MAYNA RD ETAL 2,234,912

1 AIR DUCT DAMPER Filed April 6. 1939 4 Sheets-Sheet 1 FIG. 1

FIG- 4* INVENTOR BY PHUL 0. COLLINJ' ATTO RNEY June 2, 1942. J. E.MAYNARD ETAL- 2,284,912

AIR DUCT DAMPER Filed April 6, 1959' 4 Sheets-Sheet 2 a FIG. 8 FIG. 9 i23 '22 g INVENTOR J. EHRLE MHYMQRD BY PHUL 0. 60LL1N$ 4 ATTdRNEY a June2, 1942'.

J. E. MAYNARD ETAL 2,284,912

AIR DuT DAMPER Filed, April 6, 1939 4' Sheets-Sheet 3 FIG- 16 INVENTORJ. E/IRLE MHYA/ARD BY PHUL o. c0LLIN8 ATTORNEY June 1942- J. E. MAYNARDET AL 2,284,912

AIR DUCT DAMPER Filed April 6. 1939 4 Sheets-Sheet 4 FIG. 24

INVENTOR LEARLE'MHYAHHD BY PAUL 0. COLLINS rm. 2 s

Patented June 2, 1942 AIR DUCT D'AllIPER John Earle Maynard and Paul 0.

Elyria, Ohio Collins,

Application April 6, 1939, Serial No. 266,439

11 Claims.

This invention relates to duct dampers and more particularly to animproved damper construction for use in air conducting systems and thelike.

Until the relatively recent developments in air conditioning systems nota great deal of attention has been paid to improvements in airconducting systems and particularly in the damper part of the equipment.

An object of the present invention is to provide an improved damperarrangement for the control of conducted air that introduces a staticpressure and an extended plenum chamber in advance of the damper.

Another object is to provide an air conditioning stack head damper in anair duct and the like, that is substantially without objectionableleakage to the outside of the duct and that is substantially free fromsound effects caused by the presence of small apertures in the path ofthe flow of air.

A further object is to provide a damper that is balanced uniformly sothat objectionable vibration induced by the dynamic head of the air flow'is substantially damped out.

Another object is to provide a damper that eliminates the necessity ofhaving cross dampers that are associated with undesirable turbulence.

Another object is to provide a damper that may be installed or replacedin the. stackhead and air outlet without the necessity of removing theair duct and Without the necessity of destroying and rebuilding thefinish about the installation.

A further object is to provide an improved damper assembly that providesa smoothly Working damper that adapts itself for accurate and rapidadjustment and that retains'that adjustment over a long period of time.

Another object is to provide a damper arrangement that diminishes thepressure loss ahead of the damper and that tends to reduce the pressureto be maintained in the air duct system.

A further object is to provide air conducting systems with damperarrangements that are adapted for use in the control of heating effectsin the Winter and cooling effects in the summer with a minimum of effortof adjustment.

Another object is to provide a damper that can be readily installed atconvenient locations *whereas many prior dampers were located in placesthat were practically inaccessible.

A further object is to provide a simply constructed damper for air ductsand the like that is adapted for inexpensive and rapid manufac- 55 tureand installation, that is entirely satisfactory in service, and that isof long life.

With the above and other objects in view that will be apparent to thosewho are familiar with the art to which the present invention pertainsfrom the following description of adaptations of the invention, suitableillustrative embodiments of the invention are disclosed in theaccompanying drawings, wherein:

Fig. 1 is a perspective view of a damper that embodies the presentinvention mounted in an air duct;

Fig. 2 is an enlarged section taken along the line 22 of Fig. 1;

Fig. 3 is an enlarged section taken along the line 3-3 of Fig. 1;

Fig. 4 is an enlarged perspective of the damper operating part of themechanism that is shown in Fig. 1;

Fig. 5 is a section of an installation wherein the damper operatingscrew is disposed in angular relation with the side walls of the ductand the central damper aperture is substantially closed at all positionsof the damper;

Fig. 6 is a plan view of the strap in which the front end of the damperoperating screw in Fig. 5 is journalled;

Fig. 7 is a fragmentary section of the front end journal of the damperoperating screw which is provided with a guide for positioning thescrewdriver blade in the slot in the screw;

Fig. 8 is a plan of a broken washer that seats in a groove in the screwto lock it in position;

Fig. 9 is a plan view of a spring steel locking pin that secures thedamper screw in position;

Fig. 10 is a fragmentary view, partly in section, of the damper hingerod journalled through the side walls of the duct and sealed with dropsof solder or the like, against the objectionable loss of air;

Fig. 11 is a fragmentary plan of a modified damper screw nut that swingsfrom the damper on closed links;

Fig. 12 is a section taken along the line l2-l2 of Fig. 11;

Fig. 13 is a section of the duct and damper wherein the damper screw issecured at its forward end only;

Fig. 14 is the slotted strap in which the damper screw is journalled inFig. 13;

Fig. 15 is a plan view of the damper operating means taken from the lineIii-I5 in Fig. 13;

Fig. 16 is a plan view of a solid damper screw nut;

Fig. 1'7 is a section taken along the line ll'|1 in Fig. 16;

Fig. 18 is a section of the floating screw construction with a modifieddamper operating mechanism wherein the screw threads through a rod nutthat is journalled in depressions in both the damper and a plate that issecured thereto;

Fig. 19 is a perspective view partly broken away of the damper operatingmechanism that is shown in Fig. 18; a

Fig. 20 is a plan of the slit strap in which the damper screw isjournalled in Fig. 18;

Fig. 21 is a fragmentary bolt to replace th screw in Fig. 18;

Fig. 22 is a fragmentary View from above partly in section wherein thedamper screw receiving rod nut is journalled in the damper plate;

Fig. 23 is a section taken along the line 23-23 of Fig. 22;

Fig. 24 is a rear elevation of the damper that is shown in Fig. 22; and

Fig. 25 is a fragmentary front elevation of the damper operatingmechanism that is shown in Fig. 22.

The air conditioning air duct i has a rear wall 2 on which is rotatablymounted in any desired manner the damper 3, as by means of the straphinge 4. The strap hinge serves as a bearing for the rod 5 over whichthe rear edge of the damper 3 is rolled and is secured to the rear wallof the duct by suitable means, such as the bolt and nut 6, or the like.In all of the disclosed damper installations, the damper may be mountedin any suitable air conducting line. The damper is well adapted forbeing mounted in substantially the throat of an air duct, an airconducting trunk line or branch line, or other suitable part of an airconducting means or system.

The slide plate 1 overlies an aperture in the damper 3 and is guided oneach of its lateral edges by suitable means, such as the slide plateguides 8 that are preferably, although not necessarily, struck up fromthe damper 3 to permit movement of the slide plate with respect to thedamper.

The damper 3 is adjusted at a desired position in the air duct by thedamper screw 9 that makes threaded engagement with the nut Ill that isrotatably mounted in the damper in any suitable manner. In the structureshown, the diametrically projecting pins ll extend from the nut l0 andare journalled in the straps [2 that are preferably struck out of theslide plate I. The damper screw 9 is journalled at either end in thefront and the back walls of the air duct and suitably secured inposition, as by the clamp washers It or the clamp pins M, and with anydesired friction assuming means, such as the washers 15. The screw 9 isprovided with suitable tool engaging means, such as the screw driverslot H5, or the like, so that the unattached edge of the damper may bemoved toward or away from the duct wall 2. r

The positioning of the hinge 4, the nut H and the screw 9, substantiallyalong the center line of the damper 3 provides a midline support for thedamper that opposes in a balanced manner the static air head that isopposed by the damper. This construction provides a nicely operatingdamper that is noiseless and that has no objectionable vibration inoperation. The construction also responds quickly and readily toadjustment and on being adjusted retains its position satisfactorily forindefinite periods thereafter, or

may also be readily and easily readjusted with a minimum of effort. 7

In the next illustrative structure, the air duct 26 has the damper 2!hinged closely against the back wall thereof by journalling the ends ofthe rod 22, that is rolled into the'upper rear edge of the damper,through the lateral sides of the duct and sealing them therein with anysuitable material, such as the lead 23, toavoid sound effects.

The slide plate 2 3 is guided by the lateral guides 25 that are struckup from the damper 2!. The moving edges 26 of the damper 2| may, ifdesired, be curved slightly so that they make spring pressed wipingactions against the inside surfaces of the air duct by which they arecontasted.

The damper 2! is adjustably positioned in the air duct by the threadedinterengagement of the screw 2'! and the nut 23 that has curved upperand lower surfaces 29 that make closely wiping engagement with theaperture in the slide plate 24 to minimize any sound effects from thepresence of undesirable holes therein.

The damper screw is inclined with respect to the front and back walls ofthe air duct and its end that is remote from the screw driver slot 3i]is secured in place by the clamp washer i3. The end of the damper screwin which the screw driver slot 36 is disposed is journalled in theaperture Si in the strap 32 that is secured to the inner face of thefront wall of the air duct by suitable means, such as the metal screws33. The end of the damper screw in which the screw driver slot 39 isdisposed is positioned sufficiently away from the path 3 that isfollowed by the free end of a register damper that may be mounted in theregister damper frame 35 that is secured within the air duct.

This constructionprovides a damper having a three point or tripodsupport that is well adapted for the larger installations.

The screw supporting strap may be positioned differently, if desired, aswhere the strap 38 is disposed beneath the register damper frame 35 andsecured in place with suitable means such as the metal screws 35. In anyof the constructions, where preferred, the screw driver blade guidingfunnel 31 may be mounted on the end of the damper screw so that theblade of a screw driver may more readily be guided into the slot 3!).

In the structure that is shown in Fig. 11 of the accompanying drawingsthe damper screw may thread through the nut 43 that is swung in the nutaperture in the damper H by suitable means, such as the endless links orrings 62. The nut 40 may be thin, as shown, where low velocity aircurrents are used and sound effects are absent, or the nut may bereplaced by any other suitable nut that substantially fills the damperaperture, where preferred.

In the air duct and damper arrangement that is shown in Fig. 13, thedamper 45 is hinged to the back of the air duct 64 in any desiredmanner. The damper nut 48 substantially closes the damper nut apertureat all times and eliminates any tendency to produce whistling soundswith high air pressure in the air duct. The damper nut pins 41 may, ifpreferred, be driven into tapped holes at diametrical opposite positionson theperiphery of the nut, as shown, and are journalled beneath thestraps 43 that are struck up out of the damper 45, or in other suitablemeans.

The screw 55 floats in the duct by threading through the damper nut 46and by being secured to the duct by the slotted strap i that is securedto the air duct by suitable means, such as the rivets 52. The groove 53in the damper screw adjacent its screw driver slot 5 3, slips tightlyinto the journal 55 and the wings 56 are pressed slightly toward eachother so that the damper screw 58 cannot escape therefrom.

The upper and lower curved surfaces 57, on the pair of oppositely andaxially projecting lips of the damper nut 46, make wiping engagementwith the periphery of the aperture in the slide plate 58 that isslidably mounted between the guides 5Q on the damper 45.

The nut Gil, that is shown in Figs. 16 and 17, comprises a threadedcenter into which the damper screw is twisted. The nut is tapped along acommon diameter, as at 6i, and the pair of pins 62 driven into the pinholes iii. The upper and the lower surfaces 63 of the nut are curvedproperly to make wiping engagement with the periphery of the nutaperture in the slide plate so that the nut closes the nut aperture inthe slide plate or damper for substantially all positions of the damper.

Another form of damper operating mechanism is shown in Fig, 18 of thedrawings wherein both the damper $5 and the damper plate 65 aredepressed to receive and journal the nut 61 therebetween. The nut 61 issubstantially cylindrical with rounded ends and is threadeddiametrically to receive the screw 58. The damper and the damper plateare both apertured for the screw 68, so that the damper may bepositioned without binding at any desired location within the air duct69. The apertures are as short circumferentially as is practical, tominimize the passage of air around the nut. The plate 55 is secured tothe damper by suitable means, such as by the rivets H3.

The screw 68 is journalled in a suitable aperture in the strap ll thatis attached to the duct 69 by the rivets E2, or the like. The screw 68is mounted in the strap H by spreading the wings on either side of theslit l3 sufiiciently to admit the groove it of the screw therebetweenand then the wings are pressed back to their closed position. The screwgroove M preferably has inclined edges to permit sufiicient inclinationof the screw with respect to the strap ii to avoid binding of the screwwith the damper in its vari- 16, if desired, that may be rotated by theapplication of a wrench to the screw bolt head TI. The annulardepression l8 adjacent the head of the screw bolt it may be journalledin the aperture of the strap H.

The damper 80, that is shown in Fig. 22, carries the damper plate 8!that substantially conforms with the contour of the flat ended rod nut82. The damper plate M is secured to the damper by suitable means, suchas by the rivets 8-3. the damper 88 and the plate 8!. The screw 84threads diametrically thru the nut 82. The damper plate 8| may bereplaced, where preferred, by a damper nut strap with or without openend construction, as desired, that may be considered as being shown insection by Fig. 23. Ample clearance for the screw St is provided in boththe damper and the damper plate by suitable apertures 85 and 86respectively, that are disposed therein so that binding will not occurThe nut 82 is rotatably journalled between for any position of thedamper. The damper may be suspended if desired, by suitable means, notshown, that are disposed in the apertures 81.

It is to be understood that the structures that have been disclosed anddescribed herein may, where practicable, be interchanged or modified forthe purpose of gaining advantage in a particular installation and thatall structures are submitted for purposes of illustration andexplanation and that variations may be made therein without departingfrom the invention as defined in the appended claims.

What we claim is:

1. A damper assembly, comprising in combination, a damper adapted forbeing mounted in an air duct, a damper plate substantially overlying anaperture in said damper and in rigid relation with said damper, acylindrical nut of substantially a uniform diameter thruout its lengthand apertured diametrically substantially midway between its ends thatare rotatably journalled between said damper plate and said damper andsaid nut assisting in substantially uniformly obstructing the passage ofair thru said damper aperture for all adjusted positions of said damper,end portions of said plate engaging the opposite ends of said nut forarresting the axial motion thereof, and damper operating means disposedin said nut aperture for adjusting said damper in said air duct thru itsoperative engagement with said nut.

2. An air duct damper, comprising in combination, an apertured damper, acup-shaped damper plate rigidly secured to said damp-er andsubstantially overlying the aperture therein, a cylindrical rod nut orsubstantially uniform diameter thruout its length and rotatablyjournalled in said damper cup plate and substantially uniformlyobstructing the passage of air thru said damper aperture for alladjusted positions of said damper, and damper operating means engagingsaid rod nut and extending thru said damper plate and damper.

3. A damper mechanism for mounting in an air duct, comprising incombination, a damper screw bolt threaded externally over a part of thelength thereof, tool engaging means at substantially an end of saidscrew bolt, an annular depression groove in said screw bolt adjacent anend thereof, a strap rigidly mountable on a wall of said air duct andhaving a screw bolt groove journaling aperture opening outwardly of saidstrap in a screw bolt admitting slit, a pair of bendable portions ofsaid strap adjacent said slit that permit the opening of said slit forthe passing of the screw bolt groove therebetween and that serve torestrain the bolt groove from passing thru said slit and out of saidstrap aperture when the bendable portions of the strap are bent backsubstantially in the plane of the apertured end of said strap.

4. An air duct damper apparatus, comprising in combination, a screwbolt, a thread of substantially arcuate section extending along a partof screw bolt, a substantially cylindrical rod nut that is ofsubstantially a uniform diameter thruout its length and that isdiametrically tapped and threaded substantially midway between the endsthereof for mounting on said screw bolt, a damper plate overlyingcircumferentially and housing the opposite ends of said nut andjournaling the nut therein, a damper to which said damper plate issecured, and a nut end play limiting means at either end of said nut andadapted for frictionally engaging the opposite ends of said nut forcontrolling the axial movement of said nut.

5. A damper assembly for being positioned in substantially the throat ofan air duct, comprising in combination, a damper for adjusting the rateof air flow in said air duct throat, damper supporting means movablymounting said damper in said air duct, a damper operating means disposedin said air duct and by the manipulation of which said damper may bepositioned to regulate the flow of air 'in said air duct throat, a toolengaging part of said damper operating means by the engagement of whichsaid damper may be adjustably positioned, a damper operating meanssupporting means having an aperture in which said damper operating meansis journalled and a slit opening from said aperture outwardly of saiddamper operating means supporting means and thru which said damper oper-1 ating means may be introduced into said aperture, a cylindrical nut ofsubstantially uniform diameter thruout its length mounted on said damperso that both ends of said nut are journalled with respect thereto anddiametrically air duct, comprising in combination, a damper screw boltthreaded over a part of its length, tool engaging means at substantiallyan end of said screw bolt, a screw bolt and supporting strap adapted forbeing mounted on a wall of said air duct so that a portion extendssubstantially into said air duct and said screw bolt being journaled insaid inwardly extending portion of said strap,

a substantially cylindrical nut rotatably mounted on said screw bolt, adamper for adjustably controlling the air flow thru said air duct andapertured for the disposition of said screw bolt therethru, and a damperplate housing said nut and adapted for being secured to said damper andtogether with said nut substantially uniformly obstructing the passageof air thru said damper aperture for substantially all adjustedpositions of said damper.

7. A damper mechanism for mounting in an aid duct, comprising incombination, a threaded damper operating screw bolt, a substantiallycylindrical nut threading on said screw bolt intermediate the ends ofsaid nut and along substantially a diameter thereof, bolt supportingmeans in which said screw bolt is journaled, a nut housing means inwhich said cylindrical nut may rotate and disposed circumferentiallyoutwardly of said nut, and end play arresting means engaging oppositeends of said nut and forming a part of said nut housing means andlimiting the axial travel of said nut.

8. An air duct damper apparatus, comprising in combination, a spirallyexternally threaded screw bolt, a screw bolt supporting means in rigidengagement with a wall of said air duct and in which said screw bolt isrotatably journaled to maintain said bolt in substantially controlledlocation relative to said air duct, a substantially cylindrical anddiametrically apertured nut threading on said screw belt, a damperadapted for being regulated by the operation of said screw bolt, and nuthousing means in which both ends of said nut are journalled and which issubstantially rigidly mounted on said damper whereby said damper may bemoved with respect to said air duct by the rotation of said bolt.

9. An air flow regulating device, comprising in combination, a damperthat is adapted for being disposed in substantially the throat of an airconducting means and said damper having an aperture disposed therein, adamper mounting means for hingedly securing an edge of said damper to apart of said air conducting means, an externally threaded damperoperating means extending into said damper aperture and partiallyclosing said damper aperture to the passage of air therethru in anextent that is substantially the same for all operative positions of thedamper, a strap means mountable on said air conducting means forsupporting said damper operating means and in which strap means saiddamper operating means is rotatablyljournaled, a cylindrical nut thathas an internally threaded diametrically extending aperture intermediatethe ends thereof for the operative reception of said threaded damperoperating means therein, a cylindrical depression in said damper forpositioning a part of said nut therein, and a damper plate secured tosaid damper and having a depression substantially mating with andoverlying said damper depression for the journaling of said nuttherebetween.

vl0. An air flow regulating device, comprising in combination, a damperthat is adapted for be ing disposed in substantially the throat of anair conducting line, means hinging said damper to a wall of said line,damper operating means operable thru an aperture in said damper forincreasing and decreasing the inclination of said damper with respect toa wall of said air conducting line, a substantially cylindricaldiametrically apertured nut engaged by said damper operating means andsubstantially overlying said aperture in said damper for maintaining asubstantially uniform air conduction therethru for substantially alloperative positions of said damper, a damper plate overlying a part ofsaid nut so that said nut is journalled therein and rigidly secured tosaid damper, and a strap secured permanently to a wall of said line andorificed for the jcurnalling of an end of said damper operating meanstherein and slit for the admission of said damper operating means intosaid strap orifice.

11. An air duct damper adjusting apparatus, comprising in combination, ascrew bolt, a thread of substantially arcuate section extending along apart of said screw bolt, a cylindrical rod nut that is of substantiallya uniform diameter thruout its length and that is diametrically tappedand threaded substantially midway between the ends thereof for mountingon said screw bolt, a damper plate overlying and frictionally engagingpart of the circumferential face of the nut inwardly of the oppositeends thereof, and a nut and play limiting means adapted for engaging theopposite ends of said nut for limiting the axial movement thereof.

JOHN EARLE MAYNARD. PAUL O. COLLINS.

CERTIFICATE OF CORRECTION. Patent No.-. 2,28h,9 June 2, 19m. JOHN EARLEMAYNARD, ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page LL,first column, line 55, claim 6, for "bolt and" read --bo1t end-; andsecond column, line 66, for "and" before "play" read --endand that thesaid Letters Patent should be read with this correction therein that thesame may conform to the ,record of the case in the Patent Office.

Signed and sealed this 28th day of July, A. D. 19L 2.

Henry Van Arsdale, (Seal) I Acting Commissioner of Patents.

